Modern industrial processes often involve situations in which articles are required to be introduced into openings adapted to receive them, for example for despatch of the articles in a suitably protected form or for storage of the articles. Thus for example, there is often a need for flat articles in the form of photographic slides or transparencies, more especially framed slides or transparencies, to be introduced into suitable insertion pockets to be accommodated therein. The photographic slides or transparencies which are framed in an automatically operating framing machine are accordingly to be introduced into dispatch boxes in which they can be sent to the appropriate recipient. Boxes of that kind suffer from a number of disadvantages, for example they are likely to suffer from breakage, rather too readily. In addition, problems may occur in regard to the dispatching and transmission of such boxes through the mail, as the openings of mail boxes and the like, at the recipient end, are often smaller than the dimensions of the boxes. The endeavour is therefore to provide that flat articles for example in the form of slide or transparency frames are introduced into suitable insertion pockets in what are referred to as receiving cases. Cases of that kind are flat flexible cases, preferably comprising plastic foil, which have pockets arranged in pluralities in juxtaposed relationship and in succession in rows. The flat articles in the form of slide frames can thus be inserted into the respective pockets for receiving same, and the case can then be readily dispatched through the mail.
In one method of fitting slide frames into insertion pockets in a receiving case, the insertion pockets are accessible from one side and in the region of their opening have a bar portion which extends over a plurality of insertion pockets in a row and which can be pivoted upwardly relative to the lateral walls of the respective pockets. In order to insert the flat articles or slide frames into the pockets, the bar portion must be lifted up or expanded somewhat in an upward direction, transversely with respect to the general plane of the respective pocket. The bar portion may be opened above each pocket by means of an expansion member or the like in order to permit the articles such as slide frames to be automatically fitted into the respective pockets. However, because of the high operating speed required and also because of the unpredictable behaviour of the bar portion which, by virtue of its flexibility, sometimes curves upwardly and sometimes downwardly, such procedures have not hitherto been entirely successful.